Magnetic performance and microstructure characterisation of powder metallurgy Fe–6.5 wt-% Si high-silicon steel

Abstract

Powder metallurgy high-silicon steel strip (Fe-6.5 wt-% Si) was prepared by directly sintering followed by rolling using gas atomised powder with low oxygen content. Due to its poor formability, the gas atomised powder was directly sintered with something heavy of 1 kg overlaid on powder top. The relative density of sintered samples was about 94.1% and the porosity was 5.9%. The pore pinning effect prevented the formation of extremely large grains during sintering, which was beneficial for subsequent rolling. The grain size was controlled in the range of 100-300 μm. After cold rolling, a large number of sub-grain boundaries and deformation bands were generated, which increased the strength to 1190 MPa. It was worth noting that these two would disappear after annealing. Instead, ordered B2 and D0 3 phases were formed, and the texture of high-silicon steel was mainly {100}<110>. A low iron loss W10/50 value of 0.55 W kg −1 was achieved.

Potential of powder metallurgical methods to fabricate Fe-6.5Si soft magnetic components

“…6 Fe-6.5Si can be processed by powder metallurgical methods but not by conventional cold pressing due to hard workability. Studies were published about the preparation by powder rolling starting with gas-atomised powder 7 or water atomised powder 8 as well as by additive methods using laser powder bed fusion (L-PBF), 9 electron beam powder bed fusion (E-PBF) 10 or binder jetting. 11 But only powder composite cores are commercially available where Fe-6.5Si powder is moulded with organic binder resulting in low permeability cores with low losses at high frequencies for power electronic applications.…”

Performance improvement and microstructure evolution of powder metallurgy high silicon steel with phosphorus addition

“…Powder metallurgy (PM) technology can not only greatly eliminate the defect of P segregation, but also break the shackles of P upper limit in silicon steel system compared to traditional smelting methods [23–25]. Therefore, on the basis of our previous work [26], this study prepared P-containing silicon steel sheet by PM technology using gas atomised silicon steel alloy powder as raw material. After adding P element, the mixture powder was loosely sintered followed by rolling to ensure good processing performance.…”